Regensburg 2016 – wissenschaftliches Programm
O 7.8: Vortrag
Montag, 7. März 2016, 12:30–12:45, H24
Determination of the optical constants of graphene at the carbon K-edge by transmission spectroscopy — •Christine Jansing1, Hans-Christoph Mertins1, Andreas Gaupp1, Andrey Sokolov2, Markus Gilbert1, Andreas Schümmer1, Hud Wahab3, Heiko Timmers3, Suk-Ho Choi4, and Dominik Legut5 — 1Münster University of Applied Sciences, Stegerwaldstr. 39, D-48565 Steinfurt — 2HZB, Albert Einstein Str. 15, D-12489 Berlin — 3University of New South Wales, Canberra, ACT 2600, Australia — 4Kyung Hee University, Yongin 446-701, Korea — 5IT4Innovations Center, VSB-Technical University of Ostrava, CZ-708 33 Ostrava, Czech Republic
The transmission of linearly polarized synchrotron radiation through quasi-free-standing graphene, supported by a Si3N4-membrane, has been measured across the carbon K-edge. From the measured absorption spectrum, that represents the imaginary part, the real part of the refractive index has been extracted via a Kramers-Kronig transformation. Based on these detailed optical parameters, reflection spectra have been simulated for linearly polarized soft x-ray light incident on graphene-metal systems. Importantly, the simulations include the interference of light reflected from graphene and from light reflected from the metallic substrate, respectively. In addition the optical constants are compared to the ones obtained by various density function theory calculations using single-electron framework as well as the more complex many-body approaches to the electronic structure of free-standing graphene.